Mechanical time-delay device



June 20, 1950 I s. w, o ms 2,512,369

MECHANICAL TIME-DELAY DEVICE Filed March 2'7, 1947 zvL WITNESSES: INVENTOR {Z4 77 I GeoyeN/Vorna Z8 7 BY ATTORNEY Patented June 2Q, 1950 MECHANICAL TIME -DELAY DEVICE George W. Norris, Wilkinsburg, Pa., assignor to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application March 27, 1947, Serial No. 737,690

6 Claims.

My invention relates to time delay devices, and, more particularly to devices for delaying the completion of the operation of a mechanical element to which an actuating force has been applied.

Many electric switches have tripping mechanisms, which may be actuated manuallyor by electromagnetic means, that elfect the application of a force to the elements for operating the movable elements of the switch contacts. Often it is essential that the operation of the movable elements of the switch contacts be delayedgafter the tripping mechanism has been operated, by a selected interval of time;

The time delay devices heretofore in use with electric switches include complicatedescapement mechanisms, dashpots, vanes, etc. These devices have been found to require frequent attention and are as a rule rather complicated and expensive. Often certain elements require close tolerances in the manufacture. 1

One specific object of my invention is the provision of a time delay between the tripping operation of a switch and the'completion of the operation of the movableswitch contacts that either close or interrupt a circuit.-

A broad object of my invention is the provision of simple, inexpensive and reliable mechanical time delay means 'forelectric'switches.

A still broader object of myinvention is the provision of mechanical time delay means for a movable mechanical element to which an actuating force has been applied.

A somewhat more specific object of my invention is the provision of an inertia responsive time delay device for delaying the longitudinal movement of a rod, bar, or similar machine element.

Other objects and advantages will become more readily apparent from a 'study of the following specification and the accompanying drawing, in which:

Figure 1 shows a side view'of my invention as applied to an electric switch, with the parts shown in the position they will occupy before the switch actuating elements have been operated; i

Fig. 2 is a side view of the subject matter shown in Fig. l, but with the parts shown in the position they will occupy after the switch actuating elements have been actuated, but before the timing cycle has been completed;

Fig. 3 shows electromagnetic switch actuating means for the type of switch shown in Figs. 1 and 2;

Fig. 4 is a View showing certain essential elements of my invention to larger scales; andv Fig. 5 shows a modified joint.

My device is not limited to the provision of a time delay for a switch, but is herein merely shown in combination with a switch to illustrate its practical utility and to facilitate the disclosure.

In the Figs-1 and 2, the control panel I is shown as a mounting base for an electric switch and for the timing mechanism T, which I dispose in operative relation to the switch. The switch proper is shown as a contact-bar 2 resiliently mounted on the switch arm 3 pivoted at 4 to the member 5 which is, in turn, pivoted at 1. The contact bar 2 bridges a pair of contacts 6, only one of which can be seen from the side, to establish some useful electric circuit.

The member 5 may be L-shaped as shown in Fig. 1, when the switch is of the manually actuated type, or comprise a U-shaped armature as shown in Fig. 3, when the switch is of the electromagnetically actuated type. Member 5 is pivoted at l on the bracket 8 secured to the base I. A switch actuating arm, or lever, 9 is also pivoted on the bracket 8 at point 1. An overcenter spring [0 is secured, under tension, to the pins H and I2.

A spring [3, under a selected compression between the head M of bolt !5 and the arm 3, firmly holds arm 3 against the upwardly directed leg of member 5.

When the lever 9 is moved counterclockwise about the pivot 1, the line joining the center of the pins II and I2 falls above the pivot l with the result that member 5 moves clockwise with a snap action. The contact bar 2, however, does not immediately bridge the contacts 6 since my timing mechanism T prevents such operation.

The lower end of the switch arm 3 has an element I6 bent rearwardly at right angles to the lower end ll. The element 15 is provided with a bifurcated, or slotted, end to receive the stem I 8 between the fork ends. The head is on stem. I8 prevents the element Hi from moving upwardly and in consequence the arm 3 moves counterclockwise with the reference to the member 5 to thus compress the spring !3, as shown in Fig. 2.

Since the spring I3 urges the'arm in the clockwise direction, an upward pull is produced on the stem l8.

The stem I8 is guided for rectilinear motion in the bearings 20 and 2| disposed in the supporting bracket22. At the lower end of the bracket I mount an eyelet 23 having the stem 24 mounted for vertical adjustment in the slot 25. The stem 24 is threaded to receive the nuts .27 for locking the eyelet into any vertical position within the range of the slot 25.

pected, then the use The eyelet has a hole (as the word eyelet implies) of a special internal peripheral side wall. The internal side wall has the sectional appearance of a nut with a single thread, except that it is not a thread but a single wedge shaped annulus with the internal peripheral points of the wedge all falling in a plane normal to the plane of the eyelet.

Disposed in the eyelet is the threaded stem or rod 28. The threads of this rod may be standard or have any other known pitch. The rod has a single thread and the sectional contourshould be such that the pointed tooth of the annulus fits into the thread. This is shown at 3! in; Fig. 4. The minimum diameter of the hole in the eyelet is so chosen that it is equal to or preferably just a very small fraction of the dimensions greater than the mean diameter of the threads on the rod 28.

This means that when the tooth 32, as seen in Fig. 4, is at the bottom of the thread at 3|, then the apex 33 will clear the apex 34. Now, as an upward pull is applied to stem 18, an upward pull is applied to rod 28 through the link type universal joint 38. The tooth 32 thus produces a counterclockwise force on the rod 28. Thetooth 32, at the right in Fig. 4, thus slides to the left and downwardly with reference to rod 28. At the same time the apex 33 of the tooth '32 at the left clears the apex 34 of the thread and the apex 33 moves into the bottom of the thread at 35. Since the rod 28 bears a true thread, whereas the eyelet presents a hole with a sharpedged internal periphery, the rod 28 does not oscillate back and forth in the plane of the figures, asthe simplified explanation just given seems to imply, but moves so that its lower end describes a circle with reference to a plane normal to the sheet bearing the drawings. The rod 28, while it makes its gyrations, also moves vertically and thus permits the stem l8 to move vertically.

The length of the rod 28 may be varied, the magnitude of the weight 29 maybe changed, or the longitudinal adjustment of the weight 29 may be changed with reference to rod 28, or any combinations of these changes may be made to alter the timing to be efiected.

If the tolerances are made close for the eyelet opening in relation to the threads on the stem '28, as might be desirable for a timingmechanism of my type from which a long useful life is exof the link 30 is necessary to permit gyratory motion of the region 35; The node for the gyrating rod 28 will thus be substantially in the horizontal plane of the eyelet.

'For a cheaper yet very useful construction, stem l8 and link 30 may be a single stiii' rod, as rod l8 shown in Fig. 5, thus providing but a single joint at region 36. The node of the gyrating rod 28 is then in region 36. This latter construction has been found to be quite satisfactory. To provide the loose connection at region 36, stem id is provided with threads that fit quite tight into the sleeve nut 30'. The upper'threads on rod 28' are made with a sloppy fit in the sleeve nut 30. The upper end of rod 28 is provided witha flat tongue 5| to fit looselyinto arectangular transverse slot 52 in the bottom of stem l8. By threading the sleeve nut 3E3 tightly on stem I8 to the position shown while rod 28' held in the position shown, a cheap universal joint is provided that does not come. apart because rod 28' cannot be turned.

My device thus provides for "a time delay tor had the benefit of my the rectilinear movement of stem [8 when a force is applied to it. In the application shown, the mechanism can be used with a manually operable switch as shown in Figs. 1 and 2 or with a magnetically actuated switch as shown in Fig. 3. In either case, my device provides a time delay and also positively prevents switch operation from shock.

While I have in efiect shown and described but a single embodiment of my invention, I am aware that others, particularly after they have disclosure, may devise modifications of my apparatus. I, therefore, do not wish to be'limited to the showing made but wish to be limited only by the scope of the claims hereto appended.

I claimas my invention:

1. The combination of, a base, an elongated member mounted for slidable longitudinal movement on the base, a threaded rod aligned with said member, a loose connection between one end of the rod and the adjacent end of the member, a ring disposed about the threaded rod, said ring having a sectional shape at its inner periphery to fit the threads and having an internal diameter that is equal to the diameter of the rod less one threaddepth and said ring being fixed to the base so that its axis is in alignment with the rod, means for applying a force, acting through a given distance, to the free end of said member.

2. The combination of, a base, an eyelet fixed on the base, said eyeletbeing disposed horizontally and having a circular opening such that the opposite facing edges present V-shaped projections when the eyelet is taken in any vertical section plane including the axis of the eyelet, a threaded rod disposed in the eyelet, the diameter of the rod beingso related to the diameter of the opening that the diameter of the opening is equal to the diameter of the rod less a trifle more than the thread depth, and a weight at the lower end of the rod to provide a longitudinally acting force on the rod, whereby said rod descends longitudinally at a relatively slow rate as it nutates through the eyelet.

3. In apparatus for delaying the progression in a generally longitudinal direction of an elongated member, a pendulous elongated member a base provided with a bracket having an opening therein such that opposite edges of the opening are shaped to provide V-shaped projections falling in the same plane with the apices of the Vs directed toward each other, said member being provided with V-shaped serrations at opposite outer edges, the disposition of the serrations'being such that the peaks at one side are in transverse alignment with the valleys at the other side, the peaks of the projections being so spaced that the distance between them is greater, by a relatively small fraction of the height of the projection, than the distance between the aligned valleys and peaks of the serrations, and means for applying a force longitudinally of the member to act through a given distance.

4. In apparatus for delaying the progression in a generally longitudinal direction of an elongated member, a pendulous elongated member a base provided with a bracket having an opening therein such that opposite edges of the openings are shaped to provide V-shaped projections falling in the same plane, with the apices of the Vs directed toward each other, said member beingprovided with V-shaped serrations at opposite outer edgesjthedisposition of the serrations being such that the peaks at one side are in transverse alignment with the valleys at the other side, the peaks of the projections being so spaced that the distance between them is greater, by a relatively small fraction of the height of the projection, than the distance between the aligned valleys and peaks of the serrations, means for adjusting the moment of inertia of the member about the opening in the bracket, and means for applying a force longitudinally of the member to act through a given distance.

5. In a time limit device, in combination, a base, bearing means on the base, an elongated member in the nature of a rod, or bar, mounted for slidable longitudinal movement in the bearing means, a link, a universal joint, said universal joint connecting one end of the link to one end of the member, a second universal joint, a rod having a weight at, or near, one end, said second universal joint connecting the other end of the link to the other end of the rod, said rod having threads near said other end, a ring, fixed to the base, encircling the rod at the threads, said ring being shaped at its inner periphery to fit into the threads and having a diameter at its inner periphery that is a trifle greater than the diameter of the rod less one thread depth, whereby said rod will nutate, with a node in the region of the ring, when a longitudinal pull is applied to the other end of the member to delay the slidable movement of the member.

6. In a time limit device, in combination, a base, bearing means on the base, an elongated member in the nature of a rod, or bar, mounted for slidable longitudinal movement in the bearing means, a link, a universal joint, said universal joint connecting one end of the link to one end of the member, a second universal joint, a rod having a weight at, or near, one end, means for adjusting the position of the weight longitudinally of the rod, said second universal joint connecting the other end of the link to the other end of the rod, said rod having threads near said other end, a ring, fixed to the base, encircling the rod at the threads, said ring being shaped at its inner periphery to fit into the threads and having a diameter at its inner periphery that is a trifle greater than the diameter of the rod less one thread depth, whereby said rod will nutate, with a node in the region of the ring, when a longitudinal pull is applied to the other end of the member to delay the slidable movement of the member.

GEORGE W. NORRIS.

REFERENCES CITED The following references are file of this patent:

UNITED STATES PATENTS of record in the 

